The invention is based on a valve as defined hereinafter. U.S. Pat. No. 4,647,013 has already disclosed a valve for metering a fluid, which has an actuation member, a small upper plate having an actuation opening for the actuation member, and a small lower plate having a plurality of injection ports. For opening the valve, the actuation member executes a stroke that moves the small lower plate with its injection ports away from the small upper plate and thus establishes a flow for the fluid through the valve. To uncover the opening cross section of the valve, a comparatively long stroke of the actuation member is needed. Furthermore, there is no provision for limiting the deformation of the small lower plate, for instance by providing a stop, so that a defined and constant opening cross section of the valve is not assured. The pressure of the fluid flowing through the valve exerts influence upon the size of the opening cross section of the valve, because the fluid deforms the small lower plate, and the small lower plate as a result moves farther away from the small upper plate in the region of its injection ports. Because of its severe deformation, the small lower plate runs the risk of breaking.